Here we describe the synthesis of electron-rich PXX derivatives in which the energy levels of the excited states have been rigidly shifted through the insertion of imide groups. This has allowed the development of a new series of oxygen-doped photoredox-active chromophores with improved oxidizing and reducing properties. Capitalizing on the dehalogenation of organic halides as a model reaction, we could investigate the photooxidative and photoreductive potential of these molecules in model chemical transformations. Depending on the substrate, solvent and dye the reaction mechanism can follow different paths. This prompted us to consider the first chemoselective transformation protocol, in which two different C-Br bonds could be chemoselectively reacted through the sequential photoactivation of two different colorants.
Acid-mediated transformation of tetraethyl 2,6-diethoxynaphthalene-1,4,5,8-tetracarboxylate selectively affords the core-substituted naphthalene-anhydride-ester (cNAE) in quantitative yield. This anhydride can be selectively converted into hetero-N-substituted core-functionalized naphthalene diimides (cNDIs) through sequential condensation reactions in the presence of the precursor amine with very high isolated yields over four steps. The approach can be applied to prepare a large variety of heterocyclic, aromatic, and aliphatic heterodiimides.
The tailored synthesis of homo (A2) and hetero (AB) N-substituted peri-xanthenoxanthene diimides (PXXDIs) and peri-functionalized PXX monoimides (PXXMIs) from 3-hydroxy naphthalic anhydride is described. As A2-type PXXDIs could be synthesized in one step, AB-type PXXDIs and PXXMIs were prepared through a modular approach capitalizing on sequential Suzuki coupling, Imidation and Pummerer reactions with very high yields. In view of their potential applications as organic semiconductors, self-organization studies were performed through liquid deposition on surfaces, depicting the formation of islands, needles and rods.
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